A coupler is usually needed in a liquid heater, such as an electric kettle, so that rapid socketing and separation between a heated part and a base of the electrical appliance can be realized. A diversified design of the product requires the size of the coupler to be as small as possible. However, due to the small size, demand for the coordinating precision in the existing technology is also greatly increased. In this case, manufacture deviation, as well as offset and deformation of the coupler during normal use by a consumer may cause potential quality hazard of the product. The smaller the coupler is made, the more easily the relative rotation between a male connector and a female socket connector of the coupler during coordination is jammed. Hence, in order to satisfy high demand for precise coordination, and to address the challenge on precise coordination due to the manufacture deviation and the deformation of the coupler during use, higher demand is raised for the design of the coupler.
In addition, during normal use of the liquid heater, water often drips on the base, but due to small size of the coupler, electrical parts and insulated parts therein should have more compact sizes. Therefore, the water should be expelled out of the coupler as soon as possible, so that the electric safety performance of the liquid heater when power is on will not be influenced.